Managing and using multiple calendars with YouCanBook.me (video)
Learn how to combine more than one calendar into one YouCanBook.me booking profile. Also see how you can add other people's calendars to your booking profile to check their availability too. This video refers to Google and Apple calendars. Given that there are so many variations of Microsoft email products, please visit their support page for sharing calendars.
You might also be interested in learning more about sharing calendars.